Respiratory modulation of carotid and aortic body reflex left ventricular inotropic responses in the cat
Respiratory modulation of carotid and aortic body reflex left ventricular inotropic responses in the cat
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猫颈动脉和主动脉体反射左心室正性肌力反应的呼吸调节
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
J. Jones
中科院分区：
文献类型：
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作者：
M. Daly;J. Jones
用氯氯蔗糖和氨基甲酸乙酯混合麻醉的猫，研究了左心室收缩状态下的反射变化，测量为dP/dtmax（最大压力变动率），这是对颈动脉和主动脉体化学感受器被氰化钠选择性刺激的反应。2动物采用开放气胸人工通气。心率和平均动脉血压保持不变。随着中枢呼吸活动的持续，颈动脉体的刺激引起呼吸运动的增加。左心室dP/dtmax发生可变变化，主要反应是增加。与控制值6850±450 mmHg s−1相比，平均变化8.3±2.9%。刺激主动脉体导致呼吸增加较小或无影响，但左室dP/dtmax较控制值6136±228 mmHg s−1显著增加19.6±2.9%。两组化学感受器刺激后左心室舒张末压均未发生显著变化。在暂时抑制次级呼吸机制期间重复化学感受器刺激试验：通过电刺激喉上神经的中央切端来反射性地抑制中枢呼吸驱动，并且通过停止人工呼吸使肺伸展传入活动最小化。颈动脉体刺激再次引起了不同的反应，现在最主要的是左心室dP/dtmax从5720±320 mmHg s−1的控制值下降3.1%，这与持续自发呼吸时的情况有显著不同。主动脉体刺激引起左心室dP/dtmax的增加，与持续自发呼吸时的反应相似。正性肌力反应是通过交感神经系统介导的，静脉注射β -肾上腺素能受体阻断剂心得安可以消除正性肌力反应。结论是，颈动脉体对左心室dP/dtmax的影响很小，主要的正性肌力反应是由于呼吸增加所伴随的神经源性作用。相反，对主动脉化学感受器兴奋的正性肌力反应不受呼吸调节。
1 The reflex changes in the inotropic state of the left ventricle, measured as the dP/dtmax (maximum rate of change of pressure), occurring in response to selective stimulation of the carotid and aortic body chemoreceptors by sodium cyanide, were studied in the cat anaesthetized with a mixture of chloralose and urethane. 2 The animals were artificially ventilated with an open pneumothorax. The heart rate and mean arterial blood pressure were maintained constant. 3 With on‐going central respiratory activity, stimulation of the carotid bodies caused an increase in respiratory movements. Variable changes in left ventricular dP/dtmax occurred, the predominant response being an increase. The mean change was 8.3 ± 2.9 % from a control value of 6850 ± 450 mmHg s−1. Stimulation of the aortic bodies resulted in a smaller increase in respiration or no effect, but a significant increase occurred in left ventricular dP/dtmax of 19.6 ± 2.9 % from a control value of 6136 ± 228 mmHg s−1. No significant changes in left ventricular end‐diastolic pressure occurred in response to stimulation of either group of chemoreceptors. 4 Tests of chemoreceptor stimulations were repeated during temporary suppression of the secondary respiratory mechanisms: the central respiratory drive was suppressed reflexly by electrical stimulation of the central cut ends of both superior laryngeal nerves and lung stretch afferent activity was minimized by stopping artificial respiration. Carotid body stimulation again evoked variable responses, the predominant now being a reduction in left ventricular dP/dtmax of 3.1 % from a control value of 5720 ± 320 mmHg s−1, which was significantly different to that occurring during on‐going spontaneous respiration. Aortic body stimulation caused an increase in left ventricular dP/dtmax similar to the response during on‐going spontaneous respiration. 5 The positive inotropic responses were mediated via the sympathetic nervous system, as indicated by their abolition as a result of intravenous injections of the β‐adrenoceptor blocking agent, propranolol. 6 It is concluded that the carotid bodies exert a small variable effect on left ventricular dP/dtmax, the predominant positive inotropic response being due to the concomitant neurogenic effects of the increase in respiration. In contrast, the positive inotropic response to excitation of the aortic chemoreceptors is not respiratory modulated.